Natalie Barnett: Optimising the use of pedigree information in Merino breeding programs (CSIRO/UNE scholarship)
NATALIE INITIALLY looked at the accuracy of current pedigree recording methods employed by Merino breeders. She did this by DNA fingerprinting more than 2000 pedigree animals from flocks in NSW and WA. The Wool CRC provided funds to complete the DNA fingerprints and she worked at two CRC sites to complete this work. Natalie compared the DNA fingerprints to the studs pedigree records and was able to ascertain the reliability of current pedigree recording practices. From the DNA fingerprints it was found that pedigree errors existed for 6-17% of lambs in each flock and that determining pedigrees of lambs close to the time of birth was more accurate than determining pedigrees several weeks after birth.
Knowing that pedigree errors existed Natalie then wanted to estimate the effect on genetic gain when using this incorrect pedigree information. With funding from the CRC she travelled to Denmark and worked with geneticists there for three months. During that time they developed a simulation program which estimated the effects of pedigree errors on genetic gain. When a breeding objective of increasing clean fleece weight and decreasing mean fibre diameter was simulated 25% pedigree errors reduced genetic gain in the order of 4-5%. The effect was larger when traits with lower heritabilities were included in the breeding objective.
With this information and having knowledge of the cost of current pedigree recording practices Natalie was then able to determine the cost effectiveness of current pedigree recording strategies. Having full pedigree information allows breeders to more accurately select the best animals and so increase the rate of genetic gain. Full pedigree recording will only be cost effective for breeders who are commanding premiums for genetically superior stud stock. It will also be cost effective for breeders who are running large wether flocks in addition to their stud flocks to which the added genetic gain can be passed.
Natalie also conducted benefit cost analyses of DNA fingerprinting as a pedigree recording system, knowing that pedigree information from DNA fingerprinting is very close to 100% accurate. DNA fingerprinting will be a cost effective pedigree recording method if breeders are receiving premiums for selling rams with a guaranteed pedigree which are genetically superior. It will also be a cost effective option if breeders are additionally running large wether flocks. Natalie is still working on optimal ways that breeders can incorporate DNA fingerprinting into their flocks. She has just submitted her thesis.
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